TY  - JOUR
AU  - Du, Xiaoyan
AU  - Heumueller, Thomas
AU  - Gruber, Wolfgang
AU  - Almora, Osbel
AU  - Classen, Andrej
AU  - Qu, Jianfei
AU  - He, Feng
AU  - Unruh, Tobias
AU  - Li, Ning
AU  - Brabec, Christoph J.
TI  - Unraveling the Microstructure‐Related Device Stability for Polymer Solar Cells Based on Nonfullerene Small‐Molecular Acceptors
JO  - Advanced materials
VL  - 32
IS  - 16
SN  - 1521-4095
CY  - Weinheim
PB  - Wiley-VCH
M1  - FZJ-2021-00722
SP  - 1908305
PY  - 2020
AB  - As the power conversion efficiency (PCE) of organic solar cells (OSCs) has surpassed the 17% baseline, the long‐term stability of highly efficient OSCs is essential for the practical application of this photovoltaic technology. Here, the photostability and possible degradation mechanisms of three state‐of‐the‐art polymer donors with a commonly used nonfullerene acceptor (NFA), IT‐4F, are investigated. The active‐layer materials show excellent intrinsic photostability. The initial morphology, in particular the mixed region, causes degradation predominantly in the fill factor (FF) under illumination. Electron traps are formed due to the reorganization of polymers and diffusion‐limited aggregation of NFAs to assemble small isolated acceptor domains under illumination. These electron traps lead to losses mainly in FF, which is in contradistinction to the degradation mechanisms observed for fullerene‐based OSCs. Control of the composition of NFAs close to the thermodynamic equilibrium limit while keeping adequate electron percolation and improving the initial polymer and NFA ordering are of the essence to stabilize the FF in NFA‐based solar cells, which may be the key tactics to develop next‐generation OSCs with high efficiency as well as excellent stability.
LB  - PUB:(DE-HGF)16
C6  - 32108389
UR  - <Go to ISI:>//WOS:000516873200001
DO  - DOI:10.1002/adma.201908305
UR  - https://juser.fz-juelich.de/record/890133
ER  -